I define as “submarine statutes” a category of statutes that affect the meaning of later-passed statutes. A submarine statute calls for courts to apply future statutes differently than they would have otherwise. An example is the Religious Freedom Restoration Act, which requires, in some circumstances, exemptions for religious exercise from otherwise compulsory statutory requirements. A new statute can only be understood if its interaction with RFRA is also understood. While scholars have debated the constitutionality of some statutes like these, mainly analyzing the legitimacy of their entrenching quality, I argue that submarine statutes carry an overlooked cost. Namely, they add complexity to the legal background of which a legislator must be aware if he or she is sensibly to express an intention in a new piece of legislation. The thicker the legislative waters are with submarines, the more legislatures are called to make common-law-like surveys of the legal landscape in order to understand the legislation they draft. I discuss several options for controlling the cognitive cost submarines impose on future legislation, including quasi-constitutionalization, super-statutization, and segregation.